Pressurized containers are in common use today for packaging and dispensing various fluid products. Particularly popular are aerosol cans. In general, these containers are safe and reliable, however, under certain conditions, such as exposure to high heat, the containers are liable to rupture violently due to build up of excessive internal pressure from expansion of the can contents. The rupturing of the pressurized container often results in fragments of the container being ejected at great speed and these fragments can do a great deal of damage or cause injuries.
In the past, numerous attempts have been made to solve the problem of explosive rupturing of pressurized containers. A common solution has been to provide weakened areas in the walls or base of the container designed to safely rupture and vent excess pressure at pressures below those that would cause more violent ruptures. Examples of this type of system are found in the following patents:
U.S. Pat. No. 2,795,350 to Lapin PA1 U.S. Pat. No. 2,951,614 to Greene PA1 U.S. Pat. No. 3,074,602 to Shillady PA1 U.S. Pat. No. 3,283,960 to Williams PA1 U.S. Pat. No. 3,724,727 to Zundel PA1 U.S. Pat. No. 3,786,967 to Giocomo et al. PA1 U.S. Pat. No. 3,815,534 to Kneusel PA1 U.S. Pat. No. 3,826,412 to Kneusel PA1 U.S. Pat. No. 3,831,822 to Zundel PA1 U.S. Pat. No. 3,850,339 to Kinkel PA1 U.S. Pat. No. 4,003,505 to Hardt PA1 U.S. Pat. No. 4,416,388 to Mulawski PA1 U.S. Pat. No. 4,513,874 to Mulawski PA1 U.S. Pat. No. 4,576,303 to Mundt et al. PA1 U.S. Pat. No. 4,588,101 to Ruegg
A serious drawback to these weakened areas is that they are prone to breakage and leakage of the container contents during normal handling and use.
Other techniques to solve the problem of rupturing have involved the use of auxiliary pressure relief valves incorporated in the container wall as shown in U.S. Pat. Nos. 3,245,578 to Sutton, 3,405,838 to Preisendanz and 3,515,308 to Hayes et al.
U.S. Pat. No. 3,680,743 to Reinnagel shows a safety venting system that uses a sharpened barb to pierce the wall of the container as it expands due to excess pressure.
U.S. Pat. No. 3,450,305 discloses venting means for a container that employs an end closure that is adapted to separate from the container when excess internal pressure is created due to heating. The disadvantage of this arrangement is that the separation of the end closure can often be quite violent and the expelled end closure can be as dangerous as the shrapnel of an exploded container.